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Update:
 9.02.2013r. godz. 20.00

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My antenna for 70MHz

Locator map 70MHz








Transverter TS70     Assembly TS70     Amplifier PA70     Kit's, projects and others



Amplifier PA70

This page as PDF



PA70 - Power Amplifier 70MHz




The amplifier is executed on transistor MITSUBISHI - RD16HHF1.

Construction of the amplifier is simple and fast. The plate is one-sided, plated with solder mask. This amplifier is dedicated to transverters TS70 and TH70.

Below is a schematic diagram of the amplifier:



Pictures are made on the basis of self-made prototype board.

First step is to cut out the place for the power transistor. Then we must routes the M3 threaded holes to mount the plate to the heat sink and the transistor.



Next we can solder capacitors, resistors, 1N4148, two small chokes, trimmer R3 and goldpins to the prepared plate.





Air coils enameled wire 1mm, diameter 6,5mm.



Montage LPF 70MHz. And if we have the instruments, measure the filter.



Meter - NWT500



And the results:



Performance of the filter several times, confirm repeatability.


Montage coils and chokes and other components. At the end the power transistor. Please spread it on the bottom of the heat conductive paste.



The source of the transistor is additionally connected to ground. The partial assembly looks like this:



After installation, set R3 5k (or 4.7 k) to 0V, the slider on the GND. Connect dummy load to the output. Connect the voltage to pin "+ PTT (+13,8V)" and "+13,8V". Next switch on power. Set the current Id to 180mA (max 200mA). Turn off the power. Connect PA and transverter TH70 or TS70 and our TRX.

Reduce power in TRX to 5W or less !!!






Turn on the power again. Turn on transceiver. Press the PTT switch on the microphone. It should light up red led in transverter. Switch off PTT.

Set on RTTY emissions. Press the PTT. Adjust trimmers: C16, C17 and C18 to the highest output power. The maximum output power is 10 watts.

Set the SSB emissions. Make a QSO or listen to other receiver. If necessary, increase the current Id (max 200-210mA - see datasheet).

Do it carefully!


Amplifier installation diagram:



I tested the amplifier with transverter TS70 and FT-857D.

Meter: SCHLUMBERGER SI 4031 STABILOCK:



Test results: power - 10 watts output



Harmonics picture



Good luck in building and see you on the 70 MHz band !!!


If you have any questions - write !      sp2dmb(at)gmail.com






Videos on youtube - copy link:


Transverter TH70:  http://www.youtube.com/watch?v=oDt_M8Wuu0c

Transverter TS70:  http://www.youtube.com/watch?v=d8L463Ma72U

Final test:  http://www.youtube.com/watch?v=wHLpQ5afwEE

This page as PDF




Transverter TS70       Assembly TS70       Amplifier PA70


73 de Peter SP2DMB

   

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